Background: Online interventions for mental diseases, like depression, are proven effective, but it’s unclear how treatment adherence influences the outcomes. The purpose of this research is to determine an optimum point of adherence for the online intervention Living to the full where depressive and anxiety symptoms are clinical relevant reduced and where attending to more lessons have limited value. Additionally, this research also determines whether there is a difference of optimum adherence point between the intervention with personalized feedback versus automatically feedback.
Method: Secondary analyses where done, based on previously conducted Randomized Controlled Trials (RCT’s) for Living to the full. This research includes 321 subjects with mild to moderate depression and/or anxiety symptoms. All subjects participated in the online intervention Living to the full, based on Acceptance and Commitment Therapy (ACT). Receiver Operation Characeteristic curves (ROC-curves) were used to calculate the optimum point of adherence. This is the point at which on one hand clinical relevant improvement is seen and on the other hand the added value of taking part in more lessons is limited.
Results: Results show a significance symptom reduction for depression and anxiety symptoms, for both ways of receiving feedback. These decreasing symptoms show a high levels of effect-sizes (d = .73 – 1.13). Personal feedback and automatic feedback both show a curvilinear dose-response relationship (r = .24 – .62). Generally, after seven to eight (of nine) lessons a clinically relevant decrease is shown and further lessons are unnecessary to take. Looking at the differences of optimum adherence point between the intervention with personalized feedback and automatically feedback we see that the added value off the lessons decreases after six lessons for automatically feedback and after eight lessons for personalized feedback. The symptom reduction for personal feedback is, moreover, greater than for automatic feedback (p < .05).
Conclusion: The intervention with personal feedback will not have to be shortened. The intervention with automatic feedback can be shortened three lessons to still remain optimal benefit. However, personal feedback will provide more symptom reduction than automatic feedback. To lower the costs and get the optimum efficiency, there can be looked at an indication towards personal feedback and automatic feedback.